He said while he understood concerns, he thought the delivery of the missiles could "help restrain some hot-heads considering a scenario to give an international dimension to this conflict".

However Israel issued a veiled threat to Russia over the prospect of the delivery. Israeli Defence Minister Moshe Yaalon said the Russian missile systems had not yet left Russia.

"I hope they will not leave, and if, God forbid, they reach Syria, we will know what to do," he said.

The S300 missiles would make it difficult to conduct air operations over Syria or create a no-fly zone, the New York Times reports. Israel has carried out three air strikes on Syria this year, in a bid to stop missiles coming close to their border.

The EU's arms embargo was due to expire at the end of the month and talks appeared to have faltered earlier on agreeing a new common position for the 27 member states.

William Hague has hailed the EU's "right decision" to end the embargo on supplying arms to opposition forces in Syria, despite fears from British politicians weapons could fall into the wrong hands.

Hague, who had led efforts for the restrictions on weapons to be relaxed, said "no immediate decision" would be made on sending arms to rebels fighting Bashar Assad's regime.

Following a marathon meeting in Brussels last night, Hague said lifting the embargo was "necessary and right" but insisted the Government's focus remained on ensuring successful peace talks at Geneva next month and a "political transition" in Syria.

Our policy is decided by us in the United Kingdom, not by Russia or anybody else,” he told the BBC.

“We don’t approve of Russia’s own supplies to the regime,” he said. “Russia has blocked at the UN Council every attempt that we have made so far to bring an end to this conflict so far, so we have found new ways of working with them. But it doesn’t mean our policies or views are identical.”

Mr. Hague added: “The long-term supply of weapons to the regime from Russia and from other countries has not helped this situation, therefore we do all have to think of the options we can pursue.”